Membrane Pump with Bleed Valve

ABSTRACT

A suction pump, in particular a breast pump, comprises a bleed valve with a bleed opening ( 44, 54, 67 ), a bleed body ( 32 ) which seals the bleed opening and an operating means ( 8 ) for operating the bleed body. The bleed body may be operated such that upon opening the valve initially only a partial region of the bleed opening is released and subsequently a greater part thereof or the whole bleed opening is released. Said suction pump provides a large functionality with the smallest size and, furthermore, is cheap to produce and easily assembled.

TECHNICAL FIELD

The invention relates to a method for actuating a suction pump with anair release valve according to the preamble of patent claim 1, a suctionpump with an air release valve according to the preamble of patentclaims 5 and 19, and a suction pump with a safety valve according to thepreamble of patent claim 28.

PRIOR ART

Suction pumps are known for a wide variety of applications. However,they can preferably be used in breast pump devices for pumping offbreast milk, or as drainage pumps for suctioning off body fluids.

There are suction pumps in closed systems which at all times move thesame air within the pump chamber. However, open pump systems are alsoknown with an air release valve which can be opened cyclically via anelectromagnet.

The requirements placed on these suction pumps, in particular when theyare used as breast pumps, are quite high. They should be as powerful aspossible but, at the same time, relatively small. Particularly in theiruse as breast pumps, they should be able to operate with minimummaintenance and should be easy to clean.

SUMMARY OF THE INVENTION

It is therefore an object of the invention to make available a methodfor actuating a suction pump with a safety valve, and to make availablea suction pump having an air release valve, both of these permitting thesmallest possible design of the pump yet at the same time allowing shortpump cycles.

This object is achieved by a method and by a suction pump having thefeatures of patent claims 1 and 5, respectively.

In the method according to the invention, an air release body, whichcloses an air release opening of the air release valve, is at first onlypartially lifted. In this way, a smaller force is needed than if thewhole air release opening is freed in a single step.

The means for actuating, in particular for lifting, the air release bodycan therefore be less powerful and can thus be made smaller. If anelectromagnet is used as such a means, a relatively low-power type canbe used. The reason is that, when pulling up or lifting the air releasebody, the electromagnet can at first apply less force than it does atthe end of the movement. This initially available lower force, however,is sufficient to free a relatively small opening. It is thereforepossible to use a relatively small and thus also inexpensiveelectromagnet. Moreover, the air release opening can be made relativelylarge. This ensures a rapid cancellation of the underpressure and,therefore, the desired functionality of the pump.

The pump easily reaches 120 cycles per minute. However, it can alsooperate optimally at a cycle rate of 50-72 cycles per minute. The firstcycle rate is particularly suitable for stimulation, the second one forexpression of breast milk.

In a preferred variant of the method according to the invention, only anedge area of the air release body is at first removed from the airrelease opening. A minimal amount of force is needed if this edge areacoincides with a corner of the air release body.

The air release body is preferably a membrane. The lifting of its edgearea is made easier if the lifted edge area is less thick than the restof the membrane. The air release opening is preferably polygonal, inparticular square or triangular. The membrane too is preferablypolygonal, preferably square or triangular.

To permit easier lifting of the membrane, a connecting pin can besecured to it or integrally formed on it, and this connecting pin isconnected to an armature of the lifting magnet. This connecting pin ispreferably situated in the edge area of the membrane that covers the airrelease opening. However, the membrane can also be designed with araised flange, in which case the connecting pin is not arranged over theair release opening but instead on this raised flange.

If the connecting pin is designed so as to be movable relative to themembrane, it is possible to overcome any production-related orassembly-related tolerances. Errors in the angle of the electromagnetcan also be compensated. Good results were achieved using a connectingpin which is formed integrally on an air release membrane made ofsilicone and which, by means of suitable thickening of the material, hassufficient stiffness. It can be formed thereon in a hinged manner.However, in a simple embodiment, the elasticity of the material of theconnecting pin suffices to make it movable about its point ofattachment.

In another embodiment, the air release body has a first subsidiary bodyand a second subsidiary body. A first subsidiary body closes the airrelease opening only partially, since it has an air release channelwhich creates a connection from the air release opening to the outside.This first subsidiary body including the air release channel can beclosed by a second subsidiary body. When air is released, only the firstsubsidiary body is at first lifted, or distanced from the air releasechannel, such that only part of the air release opening is freed. Thesecond subsidiary body can then also be distanced from it, such that thewhole air release opening is now freed. In this second stage, the secondsubsidiary body can preferably be actuated jointly with the firstsubsidiary body.

Compared to this embodiment, the first embodiment mentioned, with theair release membrane that can be actuated in an edge area, has theadvantage that it ensures leaktightness and thus, particularly when usedin a breast pump, ensures there is no leakage of the pumped-off milk.

A further advantage of the abovementioned embodiments, particularly asregards the use of the membrane, is that no springs are needed, and thenumber of individual parts required can therefore be reduced. Since nospring has to be fitted, the work involved in assembling the pump isalso reduced.

It is a further object of the invention to create a suction pump whichcan be put together as easily as possible.

This object is achieved by a suction pump having the features of patentclaim 19.

The suction pump according to the invention has an air release valvewith an air release membrane, and this air release membrane and a vacuummembrane used to generate the vacuum are designed integrally in the formof a common membrane plate.

Arranging the air release valve and the vacuum membrane on the sameplate means that these elements are less expensive to produce and areeasier to assemble.

In a preferred embodiment, the pump comprises an upper housing part, amiddle housing part and a lower housing part, with a membrane plate anda valve plate being arranged between the housing parts. This divisionmeans that several elements can be formed on the same structural part.In particular, the vacuum membrane needed to generate the underpressure,and the air release membrane needed to rapidly cancel the underpressure,can be formed integrally on the same structural part. Control flaps andvalve flaps can also be formed integrally on a common structural part.Electric motor and electromagnet can be secured in the same housingpart. By dividing the pump into several levels, preferably five levels,the number of individual parts can be reduced to a minimum withouthaving to give up the complexity of the pump assembly. This not onlyreduces the outer dimensions of the pump assembly, but also minimizesthe production and assembly costs.

A further advantage of this modular construction with several levels isthat the pump can be cleaned by simple flushing, without having to bedismantled into its individual parts. By virtue of the exhaust leadingto the outside, no sponge is needed. Such sponges are used in the priorart to absorb milk that has been sucked into the pump and also toattenuate noise. However, they take up space in the pump and tend togive rise to unpleasant odor.

This modular construction can also be used in a pump that does not havethe abovementioned air release valve according to the invention.

It is a further object of the invention to make available a suction pumpwhich has a safety valve and which cannot be inactivated by liquid, inparticular milk, that has been sucked into the pump and has accumulatedthere.

This object is achieved by a suction pump having the features of patentclaim 28.

The suction pump according to the invention has a safety valve with afirst stage which opens at a first underpressure, and with a secondstage which opens at a second underpressure. The first underpressure isquantitatively lower than the second.

This two-stage design of the safety valve ensures that milk cannot getas far as the second stage. Since the first stage opens even in theevent of a very slight deviation from the ideal underpressure, it willstill open, in the event of clogging, when the underpressure is at ahigher level, that is to say in an emergency situation. The second valveprevents the entire safety valve from opening at too small a deviation,but it still opens reliably in an emergency situation. This two-stagesafety valve can also be used in a pump that does not have theabovementioned air release valve according to the invention or themodular construction.

The suction pump according to the invention can therefore reduce thevacuum in a relatively short time and without too much force. The pumpaccording to the invention is suitable for a wide variety ofapplications. It is suitable in particular as a breast pump forsuctioning off breast milk and as a drainage pump for suctioning offbody fluids. The pump assembly according to the invention is suitable inparticular for use in a portable breast pump, as is described inparticular in still to be published PCT/CH 2004/000061.

Further advantageous embodiments are set forth in the attached patentclaims.

BRIEF DESCRIPTION OF THE DRAWINGS

The subject matter of the invention is explained below on the basis ofpreferred illustrative embodiments depicted in the attached drawings, inwhich:

FIG. 1 shows a perspective view of the suction pump according to theinvention without outer housing;

FIG. 2 shows a view of the suction pump according to FIG. 1 from below;

FIG. 3 shows a longitudinal section through the suction pump accordingto FIG. 1;

FIG. 4 shows an exploded view of the suction pump according to FIG. 1;

FIG. 5 shows a perspective view of a lower housing part of the suctionpump according to FIG. 1;

FIG. 6 shows a view of a membrane plate of the suction pump according toFIG. 1 from above;

FIG. 7 shows a longitudinal section through the membrane plate accordingto FIG. 6;

FIG. 8 shows an enlarged detail of the membrane plate according to FIG.7;

FIG. 9 shows a view into a part of the upper housing part from above;

FIG. 10 shows a view of a membrane plate of the suction pump accordingto a second embodiment from above;

FIG. 11 shows a longitudinal section through the membrane plateaccording to FIG. 10;

FIG. 12 shows an enlarged detail of the membrane plate according to FIG.11, and

FIG. 13 shows a longitudinal section through an air release unitaccording to the invention in a third embodiment.

EMBODIMENTS OF THE INVENTION

FIG. 1 shows a suction pump according to the invention, such as issuitable in particular for a breast pump device for pumping off humanbreast milk. However, the pump is also suitable for other applications,for example for drainage pumps for suctioning off body fluids.

Only the actual pump assembly is shown. This assembly is usuallyarranged in an outer housing. The figure does not show this outerhousing and the electronics needed for actuating the pump, or any energystorage means, for example an accumulator or battery.

The pump has an extremely compact structure. One of its largest elementsis an electric motor 1. It also has an upper housing part 2, a middlehousing part 4 and a lower housing part 6, which can be pluggedtogether. An attachment part 7 is also provided which is a componentpart of these housing parts or, as is the case here, is plugged ontothem.

On the attachment part 7, there is at least one breast shield attachmentpiece 70 on which a connecting tube to a breast shield can be plugged.The attachment part 7 also comprises an exhaust 71. This exhaust 71 alsoleads out of the outer housing. An air release channel 72, alsoprotruding from the outer housing, and spacer elements 73 are alsopresent. The spacer elements 73 brace the pump assembly in relation toan outer housing in such a way that vibrations cannot be transmitted anda sufficient sound insulation is ensured.

It will be seen from FIG. 2 how the individual attachments 70, 71, 72are connected via individual channels to the individual areas of thepump.

The longitudinal section shown in FIG. 3 through the pump, now withoutmotor 1, shows that the pump, despite its compact design, is dividedinto three clearly distinguishable function areas: a pump unit P, an airrelease unit V and, arranged between these, a safety unit S. Thestructure of the pump can best be seen from an overview of FIGS. 3 and4.

The pump unit P comprises a vacuum membrane 31 and inlet and outletcontrol flaps 51, 52 which, together with inlet and outlet openings 62,63 and with a pump chamber opening 43′, create a connection between apump chamber 43 and a vacuum channel 69. The vacuum membrane 31 isconnected to a drive shaft 10 of the electric motor 1 via a connectingrod 11, coupling piece 12, for example a ball bearing, and eccentric 13and, by means of this motor 1, it can be lifted and lowered according toa predetermined rhythm or pump curve or according to a rhythm or pumpcurve that can be freely selected via a control system.

The air release unit V comprises an air release valve with an airrelease membrane 32, and an air release opening which can be closedtightly by the latter and is in the form of an air release membrane seat44. The chamber 44′ surrounding the air release membrane seat 44 isconnected via an air release attachment 45 to the air release channel72. The air release membrane seat 44 is open at the bottom, that is tosay on the side directed away from the air release membrane 32, andadjoins a first air release opening 54 of the valve plate 5 and a secondair release opening 67 of the lower housing part 6. This second airrelease opening 67 is connected via the vacuum channel 69 to a safetyvalve chamber 68 and to the inlet opening 62.

The air release membrane 32 is connected via a connecting pin 33 to anarmature 80 of a lifting magnet or electromagnet 8. The electromagnet 8lifts the air release membrane 32 and thus frees the air releasemembrane seat 44. By this means, air passes through the air releasechannel 72 and through the first and second air release openings 54, 67into the vacuum channel 69, and the underpressure in the latter isreduced. This lifting and lowering of the air release membrane 32 alsotakes place according to a predetermined function or according to afunction that can be freely selected via a control system, and whichfunction is coordinated with the movement of the vacuum membrane 31. Themovements of the vacuum membrane 31 and of the air release membrane 32are preferably coordinated in such a way that a pump curve is obtainedwhich is as described in WO 01/47577 and which is adapted to the needsof mother and child or imitates the natural sucking rhythm of a baby.The assembly functions in all positions, that is to say, for example,when it is lying or standing on a table or being carried. The vacuumgenerated is largely independent of how the assembly is spatiallyarranged.

The safety unit S comprises a safety valve. In the event of amalfunction or failure of the control electronics that coordinate themovement of the vacuum membrane 31 and of the air release membrane 32,this safety valve ensures that the level of the underpressure in thepump does not become too great and injure the mother's breast.

According to the invention, the safety unit S is designed with twostages. The first stage consists of a first safety membrane 55 and of asemispherical safety valve closure 46 which has a small lateral opening46′ and which presses on the first safety membrane 55. This first stageopens even at a low underpressure of about 120 mmHg.

The second stage comprises a second safety membrane 35 which is closedby means of an adjusting screw 9. Its limit value, at which it opens,can be modified by adjustment of the adjusting screw 9. According to theinvention, it opens at a higher underpressure than the first stage, forexample at about 290 mmHg.

If milk or another suctioned fluid accidentally gets into the pump, itsettles in the area of the first stage and cannot pass through to thesecond stage via the chamber lying in between. At the very most,therefore, it can cover the first safety membrane 55. In this coveredstate, the latter possibly no longer opens at the preset value, but italways opens early enough to permit release. The second membrane alwaysopens only when the limit value is actually exceeded and the pump has tobe relieved. Since the second stage cannot be soiled, it always opensreliably.

The individual parts of the pump can best be seen in FIG. 4. Thisexploded view shows that the pump is divided into several levels I, II,III, IV and V, where parts of the pump unit P, of the safety unit S andof the air release unit V are arranged on common levels.

A first level I, which usually, but not necessarily, forms the uppermostlevel in the operating position, comprises the upper housing part 2, theaforementioned motor 1, and the electromagnet 8. The motor 1 is securedby fastening screws 21 onto a motor plate 20 of the upper housing part2. The motor can be screwed onto the motor plate 20 and can likewise beplugged onto the pump assembly. The housing part 2 comprises aconnecting rod chamber 23 which is used to receive the connecting rod11, the ball bearing 12 connected thereto, and an eccentric withcounterweight 13. The counterweight 13 does not necessarily have to bepresent. The upper housing part 2 also comprises a magnet chamber 24which is separate from the connecting rod chamber 23 and in which theelectromagnet 8 is secured. At its lower end, the upper housing part 2has upper locking clips 22 which protrude downward.

The adjusting screw 9 for the second stage of the safety valve is alsoarranged adjustably in the upper housing part 2.

The second level II is defined by a membrane plate 3 which extends atleast approximately across the whole base surface of the upper housingpart 2 and thus of the pump assembly. The membrane plate 3 is made of aflexible material, in particular silicone, and is relatively thin. Ithas centering holes 30 in its edge areas, and upper and lower sealinglips 34, 34′, 34″ which ensure an airtight and liquid-tight connectionto the upper housing part 2 and middle housing part 4, respectively. Thelower sealing lips can be seen in FIG. 7. The membrane plate 3 comprisesthe air release membrane 32, which is designed in the shape of atriangle. As can be seen in FIG. 6, the air release membrane 32 has atriangular basic shape. This triangle is divided into two subsidiaryareas, where a first subsidiary area 32′ again forms a triangle, and thesecond subsidiary area 32″ is formed by the remaining part of themembrane and thus has a trapezoid shape. A first corner of the firstsubsidiary area 32′ coincides with a corner of the air release membrane32. An opposite side of the first subsidiary area 32′ extends parallelto an opposite side of the air release membrane 32, and the two othersides of the triangle of the first subsidiary area 32′ extendcongruently with respect to the sides of the triangle of the air releasemembrane 32. The triangular first subsidiary area 32′ is less thick thanthe second subsidiary area 32″, as can be seen in FIGS. 7 and 8.

The connecting pin 33 is formed integrally on the free corner of thefirst subsidiary area 32′. As can also be seen from FIGS. 7 and 8, itprojects upward at least approximately perpendicular to the plane of themembrane and is fixedly connected to the armature 80. The air releasemembrane 32 is surrounded by a first sealing lip 34.

The membrane plate 3 further comprises the vacuum membrane 31, which isconnected to the connecting rod 11. The connecting rod 11 can be formedintegrally on the vacuum membrane 31 by material thickening and can becomposed of a two-component material. It can also be producedseparately, however, and be connected to the membrane 31 duringassembly. The vacuum membrane is sealed off from the upper and middlehousing parts 2, 4 by means of a second sealing lip 34′.

The membrane plate 3 further comprises the second membrane 35 of thesafety valve. The latter, as can best be seen in FIG. 7, has a v-shapedopening that widens toward the bottom and is sealed off from the upperand middle housing parts 2, 4 by means of a third sealing lip 34″ thatsurrounds it.

The third level III is formed by the middle housing part 4. Like theupper and lower housing parts 2, 6, it is preferably made of a solidplastic material, for example POM (polyoxymethylene). The middle housingpart 4 is panel-shaped and has a plane upper face and a plane lowerface. On its side faces, it is provided with upwardly and downwardlydirected catches 40, 41, respectively, the upper catches 40 engaginginto the upper locking clips 22 of the upper housing part 2, and thelower catches 41 engaging into lower locking clips 60 of the lowerhousing part 6. Centering holes 42 are also present which are inalignment with the centering holes 30 of the membrane plate 3.

Two recesses, closed at the bottom and with small lateral connectingopenings, are present in the middle housing part 4. One of theserecesses forms the vacuum membrane seat 43 for the vacuum membrane andthus defines the pump chamber. A second of these recesses forms a safetyclosure 46 of the first safety stage. The chamber 44′, with the membraneseat 44 arranged therein for the air release membrane 32, is alsopresent in the middle housing part 4. This seat 44 has a triangularshape in this example. The chamber 44′ is a recessed, h-shaped trough,the latter being connected to the air release attachment 45.

The fourth level IV in turn comprises a flexible plate, preferably ofsilicone. It is formed by a valve plate 5. This too has centering holes50, at least one pair of these centering holes 50 being in alignmentwith the centering holes of the middle housing part 4 and of themembrane plate 3.

The valve plate 5 comprises a first control flap 51, which forms aninlet for the vacuum chamber. It further comprises a second control flap52, which forms an outlet for the vacuum chamber. Leading away from thesecond control flap 52, there is a double sealing lip 53 which surroundsan upwardly open connecting channel 64 arranged in the lower housingpart 6 and seals this connecting channel 64 at the top.

The first membrane 55 of the safety valve is also formed integrally inthe valve plate 5. The latter also comprises the first air releaseopening 54, which ensures a connection between the air release membraneseat 44 and a second air release opening 67, which is arranged in thelower housing part 6. The individual elements of the valve plate 5 arein turn provided with upper and lower sealing lips to seal them relativeto the middle and lower housing parts 4, 6. All the elements of thevalve plate 5 are preferably produced integrally with the latter.

The fifth level V comprises the lower housing part 6 and the attachmentpart 7. These two parts can be formed by a single common part, or, as isshown here, they can be coupled to one another by plug connections.

The lower housing part 6 is shown in FIG. 4, and in another perspectiveview in FIG. 5. It also has a plate-shaped design, its underside formingthe base of the pump assembly. The lower locking clips 60 project upwardat the sides, such that the lower catches 41 of the middle housing part4 can lock into them. Centering pins 61 are also present which alsoproject upward and can be guided through the centering holes 30, 42, 50of the membrane plate 3, of the middle housing part 4 and of the valveplate 5. These centering pins and centering holes make it easier tostack the individual levels on one another and thus permit rapidassembly.

The lower housing part 6 further comprises a first circular recess withcentral elevation, which forms an inlet opening 62. A second circularrecess forms an outlet opening 63. This inlet opening 62 is connected tothe vacuum channel 69 extending in the inside of the lower housing part6. This channel 69 first passes through the safety valve opening 68which is likewise designed as a trough and over which the safetymembrane 55 of the first stage is arranged.

The connecting channel 64, open at the top and sealed off by the sealinglip 53, extends in the lower housing part 6 and opens into the outletopening 63. This connecting channel 64 is connected to the second airrelease opening 67 present in the lower housing part 6.

As can be seen in FIG. 5, the connecting channel 64 ends in an exhaustattachment 66 which can be plugged into the exhaust 71. The second airrelease opening 67 leads to a breast shield attachment part 65, which isconnected to the breast shield attachment piece 70.

This construction permits simple cleaning of the pump. If milk oranother suctioned liquid gets into the pump, the latter can simply beflushed with water or air, the cleaning medium being pressed or blown inthrough the beast pump attachment piece 70 and leaving the pump again byway of the air release channel 72 and the exhaust 71.

FIG. 9 shows a partial view from above into the upper housing part 2. Ascan be seen here, the adjusting screw 9 of the safety valve S isdesigned with a round cross section but is screwed into a square threadopening 25. This means that a sufficient passage of air is at all timesensured.

FIGS. 10 to 12 show a second embodiment. This embodiment differs fromthe one described above in the area of the air release valve. The otherparts are of the same design and are therefore not described again here.In this example, the air release membrane 32 is not triangular, butsquare. However, it can also be hexagonal or octagonal or of any desiredpolygonal shape. It has been found in practice, however, that the squareshape closes and opens more reliably compared to the triangular shape.The air release membrane is once again divided into thick and thinsubsidiary areas 32′, 32″, the connecting pin 33 being arranged on thethin subsidiary area 32′. The two subsidiary areas 32′, 32″ are alsosubstantially square, the connecting pin 33 being arranged on a longside of the thin subsidiary area 32′ directed away from the thicksubsidiary area 32″. It is now no longer secured in a corner, butapproximately midway along this long side, as can be seen in FIG. 10. Ithas also been found that the functionality is better ensured if theconnecting pin is integrally formed on the side wall 44″ of the chamber44′, as is shown in FIG. 12. However, the opening lying below this, thatis to say the air release membrane seat 44, is preferably triangular asbefore. In this case, the connecting pin 33 is preferably arrangedexactly over the corner of the triangular hole 44.

FIG. 13 shows a further embodiment of the air release valve according tothe invention. The rest of the pump can be designed the same way asdescribed above and is therefore not shown again here. The air releasebody is not a membrane here, but instead is formed by first and secondair release blocks 320, 321.

The first air release block 320 is fixedly connected to the armature 80of the lifting magnet 8. It is connected to the second air release block321 via a first, soft spring element 322 and a retaining clip 323. Theretaining clip 323 is secured, via a second, harder spring element 324,on a base body 325 surrounding the air release body. The base body 325,the first air release block 320, the retaining clip 323 and the twospring elements 322, 324 are preferably made of plastic and are alldesigned together in one piece.

The second air release block 321 has a first air release channel 326,which can be closed by the first air release block 320. The second airrelease block 321 closes a second air release channel 327, which isconnected to the vacuum channel 69. The second air release channel 327has a greater diameter than the first air release channel 326.

If the armature 80 of the magnet 8 is now lifted, the soft springelement 322 means that only the first air release block 320 is lifted atfirst and the first air release channel 326 is freed. If the armature 80is lifted further, the magnet is then more powerful and, despite theharder spring element 324, is able to lift the second air release block321 and thus free the second air release channel 327. A connection isthereby created now between the first air release channel 326 and thevacuum channel 69, and the underpressure in the pump is reduced. As analternative or in addition to the springs of different strength,abutment elements can be provided which limit the travel of the firstand second springs.

Therefore, in this embodiment too, the air release body is lifted suchthat it at first only frees part of the air release opening, with theresult that less force is needed at the beginning of the liftingmovement than at the end of the movement.

The suction pump according to the invention therefore affords severaladvantages. It provides wide-ranging functionality within a very smallspace and can also be produced inexpensively and is easy to assemble.

LIST OF REFERENCE SIGNS

P pump unit

V air release unit

S safety unit

I first level

II second level

III third level

IV fourth level

V fifth level

1 motor

10 drive shaft

11 connecting rod

12 ball bearing

13 eccentric with counterweight

2 upper housing part

20 motor plate

21 fastening screws

22 upper locking clip

23 connecting rod chamber

24 magnet chamber

25 thread opening

3 membrane plate

30 centering hole

31 vacuum membrane

32 air release membrane

32′ first subsidiary area

32″ second subsidiary area

33 connecting pin

34 first sealing lip

34′ second sealing lip

34″ third sealing lip

35 second membrane of the safety valve

320 first air release block

321 second air release block

322 first spring element

323 retaining clip

324 second spring element

325 base body

326 first air release channel

327 second air release channel

4 middle housing part

40 upper catches

41 lower catches

42 centering hole

43 vacuum membrane seat

43′ pump chamber opening

44 air release membrane seat

44′ chamber

44″ side wall

45 air release attachment

46 safety valve closure of first stage

46′ lateral opening

5 valve plate

50 centering hole

51 first control flap

52 second control flap

53 sealing lip for connecting channel

54 first air release opening

55 first membrane of the safety valve

6 lower housing part

60 lower locking clip

61 connecting pin

62 inlet opening

63 outlet opening

64 connecting channel

65 breast shield attachment part

66 exhaust attachment

67 second air release opening

68 safety valve chamber

69 vacuum channel

7 attachment part

70 breast pump attachment piece

71 exhaust

72 air release channel

73 spacers

8 lifting magnet

80 armature

9 adjusting screw

1. A method for operating a suction pump, in particular a membrane pumpfor generating a vacuum, the suction pump having an air release valvewith an air release body which frees an air release opening at cyclicaltime intervals and closes it sealingly again, characterized in that theair release body is lifted in such a way that it at first only partiallyfrees the air release opening.
 2. The method as claimed in claim 1, inwhich the air release body is at first removed from the air releaseopening at an edge area.
 3. The method as claimed in claim 2, in whichthe air release body is at first removed at a corner of the air releaseopening.
 4. The method as claimed in claim 1, in which a first part ofthe air release body is at first lifted in order to free a first airrelease channel, and a second part of the air release body is thenlifted in order to free a second air release channel, the second airrelease channel having a greater diameter than the first air releasechannel, and the two channels being connected to one another.
 5. Asuction pump with an air release valve, the air release valve having anair release opening, an air release body which can close the air releaseopening sealingly, and an actuating means for actuating the air releasebody, characterized in that the air release body can be actuated in sucha way that, upon opening of the valve, it at first frees only a partialarea of the air release opening and thereafter frees a larger partialarea or the entire air release opening.
 6. The suction pump as claimedin claim 5, in which the air release body is an air release membrane,and in which the air release membrane has an edge area at which it canat first be removed from the air release opening upon opening of thevalve.
 7. The suction pump as claimed in claim 6, in which the actuatingmeans is a lifting magnet, and the air release membrane is connected toan armature of the lifting magnet via a connecting pin, and theconnecting pin is connected to the air release membrane at this edgearea thereof.
 8. The suction pump as claimed in claim 7, in which theconnecting pin is arranged over a corner of the air release opening. 9.The suction pump as claimed in claim 7, in which the connecting pin isformed integrally on the air release membrane.
 10. The suction pump asclaimed in claim 7, in which the connecting pin is arrangedapproximately perpendicular to the air release membrane.
 11. The suctionpump as claimed in claim 6, in which the air release membrane is made ofa plastic, in particular of silicone.
 12. The suction pump as claimed inclaim 6, in which the air release membrane has at least one corner, andthe edge area comprises at least one of the at least one corner.
 13. Thesuction pump as claimed in claim 6, in which the air release membranehas a polygonal basic shape, in particular a square or triangular basicshape.
 14. The suction pump as claimed in claim 6, in which the airrelease membrane has a first partial area with a lesser thickness and asecond partial area with a greater thickness, and in which the edge areais arranged in the first partial area.
 15. The suction pump as claimedin claims 13 or 14, in which the air release membrane has a square basicshape, in which the two partial areas each have a square basic shape,and in which the connecting pin is arranged on a long side of thethinner partial area directed away from the thicker partial area. 16.The suction pump as claimed in claim 15, in which the long side has acenter, and in which the connecting pin is arranged in the area of thiscenter on the thin partial area.
 17. The suction pump as claimed inclaim 5, in which the air release opening has a polygonal basic shape,in particular a square or triangular basic shape.
 18. The suction pumpas claimed in claim 6, in which the air release membrane issubstantially plane.
 19. A suction pump with an air release valve inwhich the air release valve has an air release membrane, and in whichthis air release membrane and a vacuum membrane used to generate thevacuum are designed integrally in the form of a common membrane plate.20. The suction pump as claimed in claim 19, in which a part of thismembrane plate is designed as a safety membrane of a safety valve. 21.The suction pump as claimed in claim 15, in which the pump comprises anupper housing part which receives a lifting magnet for actuating the airrelease membrane and receives an electric motor for actuating the vacuummembrane, a middle housing part with an air release membrane seat whichis provided for the air release membrane and which surrounds an airrelease opening, and with a vacuum membrane seat for the vacuummembrane, and a lower housing part for forming a vacuum channel betweenair release opening and an inlet opening of the vacuum membrane seat,the membrane plate being arranged between the upper and middle housingparts, and a valve plate being arranged between the middle and lowerhousing parts.
 22. The suction pump as claimed in claim 21, in which thevalve plate and the membrane plate are substantially plane.
 23. Thesuction pump as claimed in claim 21, in which the valve plate and themembrane plate are made of a plastic, in particular of silicone.
 24. Thesuction pump as claimed in claim 5, comprising an exhaust and,optionally, a vacuum attachment and an air release attachment whichprotrude from an outer housing of the pump.
 25. The suction pump asclaimed in claim 21, in which an exhaust attachment is formed integrallyon the lower housing part and can be connected to the exhaust formedintegrally on an attachment part.
 26. The suction pump as claimed inclaim 21, in which the lower, middle and upper housing parts can beplugged together so as to form a closed housing assembly.
 27. Thesuction pump as claimed in claim 26, in which the housing assembly issubstantially watertight and can be flushed through via a breast pumpattachment to the exhaust and the air release opening.
 28. A suctionpump with a safety valve in which the safety valve has a first stepwhich opens at a first underpressure, and a second step which opens at asecond underpressure, the first underpressure being quantitatively lowerthan the second.
 29. The suction pump as claimed in claim 5, in whichthe air release body has first and second subsidiary bodies, the firstsubsidiary body being connected to an armature of a lifting magnet, andthe second subsidiary body being connected to the first subsidiary bodyvia a first spring element, and the second subsidiary body having afirst air release channel which can be closed by the first subsidiarybody, the second subsidiary body closing a second air release channel,and the second air release channel having a greater diameter than thefirst air release channel.
 30. The suction pump as claimed in claim 20,in which the pump comprises an upper housing part which receives alifting magnet for actuating the air release membrane and receives anelectric motor for actuating the vacuum membrane, a middle housing partwith an air release membrane seat which is provided for the air releasemembrane and which surrounds an air release opening, and with a vacuummembrane seat for the vacuum membrane, and a lower housing part forforming a vacuum channel between air release opening and an inletopening of the vacuum membrane seat, the membrane plate being arrangedbetween the upper and middle housing parts, and a valve plate beingarranged between the middle and lower housing parts.
 31. The suctionpump as claimed in claim 22, in which the valve plate and the membraneplate are made of a plastic, in particular of silicone.
 32. The suctionpump as claimed in claim 24, in which an exhaust attachment is formedintegrally on the lower housing part and can be connected to the exhaustformed integrally on an attachment part.